JPH05220960A - Liquid jet recording head - Google Patents

Abstract

PURPOSE:To prevent a possibility that a bubble generated in a recording liquid in a flow path may come into contact with the top wall of the flow path and interrupt a flow of recording liquid by a method wherein a recessed part is formed on a part of a monocrystal silicon substrate by anisotropic etching, and an energy acting part is formed thereon. CONSTITUTION:A recessed part 16 of approximately a V shape is formed on a part of an upper surface of a monocrystal silicon substrate 15. On the upper surface of the monocrystal silicon substrate 15, discrete electrodes 4 and a common electrode 5, and heating elements 17 serving as a thermal energy acting part are formed by wafer processing. The monocrystal silicon substrate 15 is used by the following reasons: firstly, a silicon per se has a very high thermal conductivity and good heat release characteristics; secondly, a silicon oxide film 20 acting as a heat accumulation layer can be easily formed thereon; and thirdly, monocrystals having a high purity can be obtained, and the recessed part 16 of a high accuracy can be formed using the anisotropy thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid jet recording head,
More specifically, the present invention relates to a liquid jet recording head in a so-called thermal inkjet printer that uses heat to fly ink.

[0002]

2. Description of the Related Art The non-impact recording method has been attracting attention for office use and the like because noise generation during recording is so small that it can be ignored. Among them, the so-called inkjet recording method, which is capable of high-speed recording and can perform recording on plain paper without requiring a special fixing process, is an extremely powerful recording method. Various methods have been proposed, or have already been commercialized and put into practical use.

In such an ink jet recording method, small droplets of a recording liquid, so-called ink, are ejected and adhered to a recording medium for recording, and the method of generating the recording liquid droplets and the generation thereof are generated. Depending on the control method for controlling the flight direction of the recording liquid droplets, it is roughly classified into several methods.

The first method is, for example, US Pat. No. 3060.
No. 429 is disclosed. this is,
This is called a Tele type method, in which the recording liquid droplets are generated electrostatically by suction, and the generated recording liquid droplets are subjected to an electric field control according to a recording signal, and the recording liquid droplets are selectively formed on a recording medium. The recording is performed by adhering to the.

More specifically, an electric field is applied between the nozzle and the accelerating electrode to eject uniformly charged recording liquid droplets from the nozzle, and the ejected recording liquid droplets can be electrically controlled according to a recording signal. Recording is performed by flying between the xy deflection electrodes configured as described above and selectively adhering recording liquid droplets onto the recording medium according to a change in the strength of the electric field.

The second method is, for example, US Pat. No. 3,596.
No. 275, U.S. Pat. No. 3,298,030, and the like. This is called the Sweet method, and a recording liquid droplet whose charge amount is controlled is generated by the continuous vibration generating method, and this recording liquid droplet whose charge amount is controlled is applied with a uniform electric field. Recording is performed by flying between the deflection electrodes and adhering onto the recording medium.

Specifically, a charging electrode configured so that a recording signal is applied in front of an orifice (ejection port) of a nozzle, which is a part of a recording head provided with a piezoelectric vibrating element, has a predetermined distance. The piezoelectric vibrating elements are arranged apart from each other, and an electric signal having a constant frequency is applied to the piezoelectric vibrating elements to mechanically vibrate the piezoelectric vibrating elements to eject recording liquid droplets from the orifices. At this time, electric charges are electrostatically induced in the discharged recording liquid droplets by a charging electrode, and the recording liquid droplets are charged with a charge amount corresponding to a recording signal. The recording liquid droplets whose charge amount is controlled are deflected according to the added charge amount when flying between the deflection electrodes to which a constant electric field is uniformly applied, and the recording liquid droplets carry a recording signal. Only the liquid will adhere to the recording liquid and recording will be performed.

The third method is, for example, US Pat. No. 3,416.
No. 153 is disclosed. this is,
It is called a Hertz method, and is a method of applying an electric field between a nozzle and a ring-shaped charging electrode to generate and atomize recording liquid droplets by a continuous vibration generation method, and perform recording. That is, the atomization state of the recording liquid droplets is controlled by modulating the electric field strength applied between the nozzle and the charging electrode according to the recording signal, and the gradation of the recorded image is produced and recording is performed.

The fourth method is, for example, US Pat. No. 3,747.
No. 120 specification. this is,
It is called the Stemme system, and has a fundamentally different principle from the first to third systems. That is, in any of the first to third methods, the recording liquid droplets ejected from the nozzles are electrically controlled during the flight, and the recording liquid droplets carrying the recording signal are selectively covered. On the other hand, recording is performed by attaching the recording liquid onto the recording medium, whereas in the Stemme system, recording liquid droplets are ejected and ejected from an orifice according to a recording signal to perform recording.

That is, in the Stemme system, an electric recording signal is applied to a piezoelectric vibrating element attached to a recording head having an orifice for ejecting a recording liquid droplet, and the electric recording signal is applied to the mechanical of the piezoelectric vibrating element. The recording is performed by changing to the mechanical vibration, and ejecting the recording liquid droplets from the orifice in accordance with this mechanical vibration and adhering them to the recording medium.

Each of these four methods has its own characteristics, but at the same time, it has problems to be solved.

First, in the first to third methods, direct energy for generating recording liquid droplets is electric energy, and deflection control of recording liquid droplets is also electric field control. Therefore, the first method is simple in configuration, but requires high voltage to generate recording liquid droplets, and it is difficult to form the recording head with multiple nozzles, and is not suitable for high-speed recording. The second method is suitable for high-speed recording because it is possible to use a multi-nozzle recording head, but it is complicated in structure, and the electrical control of recording liquid droplets is highly advanced and difficult. Satellite dots are likely to occur on the. The third method enables recording with excellent gradation by atomizing recording liquid droplets, but on the other hand, it is difficult to control the atomization state. Further, there are drawbacks such that fog occurs in a recorded image and it is not suitable for high-speed recording because it is difficult to form a recording head with multiple nozzles.

On the other hand, the fourth method has many advantages as compared with the first to third methods. First, the configuration is simple. Further, since the recording liquid droplets are discharged on-demand from the orifices of the nozzles for recording, the recording liquid droplets ejected and ejected as in the first to third methods that are not necessary for image recording. It is not necessary to collect the droplets. Further, unlike the first and second methods, there is no need to use a conductive recording liquid, and there is an advantage that the degree of freedom in terms of the substance of the recording liquid is large. However, it is difficult to make the recording head multi-nozzle because there are problems in processing the recording head, and it is extremely difficult to downsize the piezoelectric vibrating element having a desired resonance frequency. Further, since the recording liquid droplets are ejected and ejected by the mechanical energy of the mechanical vibration of the piezo-vibration element, it is unsuitable for high-speed recording in combination with the difficulty of forming the multi-nozzle described above.

As described above, the conventional liquid jet recording method has merits and demerits in terms of configuration, high speed recording, multi-nozzle recording head, generation of satellite dots and fog of recorded image. However, there is a restriction that it can be applied only to the application in which its advantage is exerted.

However, such an inconvenience can be almost eliminated by adopting the ink jet recording system disclosed in Japanese Patent Publication No. 56-9429 proposed by the present applicant. In this method, the ink in the liquid chamber is heated to generate bubbles, thereby causing a pressure increase in the ink and ejecting the ink from a fine capillary nozzle to perform recording.

[0016]

A number of inventions utilizing this principle have been made. Among them, air bubbles generated in the flow path reach the ceiling of the flow path, thereby causing a flow of the recording liquid. Japanese Patent Application Laid-Open No. 56-139970 discloses an invention made in view of the fact that when the liquid is cut off, ejection error of recording liquid droplets, decrease in ejection speed, and disturbance in ejection direction occur. However, the publication only mentions “do not block by air bubbles”, and does not explicitly state how to do it. It is very conceptual and realization is impossible. It's difficult.

On the other hand, in the so-called thermal ink jet system in which the recording liquid droplets are ejected from the orifice by the instantaneous pressure increase due to the bubbles generated in the flow path,
About half of the pressure of the bubble acts in the direction of the orifice to be used for ejecting the recording liquid droplets, but the remaining pressure escapes in the direction opposite to the orifice, that is, to the supply side of the recording liquid.
Therefore, as an invention made under the idea of effectively utilizing this escaped pressure to improve the ejection efficiency of the recording liquid droplets, there is one disclosed in Japanese Patent Laid-Open No. 55-100169. .. According to the present invention, by providing a barrier between the information signal input section and the orifice in the liquid chamber in which the information signal input section is provided, the ejection response to the input signal is improved and adapted to high speed recording. It is a thing. However, it is technically extremely difficult to provide such a barrier in a fine flow path, and its feasibility is poor.

[0018]

The invention according to claim 1 is
A flow channel into which the recording liquid is introduced, a thermal energy acting portion that is formed on the bottom surface of the flow channel and generates bubbles in the recording liquid by heat generation, and the generation of the bubbles while communicating with the flow channel. An orifice that discharges a part of the recording liquid as a recording liquid droplet by the pressure associated with the liquid chamber, a liquid chamber that communicates with the flow channel and contains the recording liquid that is introduced into the flow channel, and a liquid chamber In a liquid jet recording head having a supply means for supplying the recording liquid, the flow path is formed on a single crystal silicon substrate, and a concave portion is formed on a part of the single crystal silicon substrate by anisotropic etching. The thermal energy acting portion was formed in the recess.

According to a second aspect of the present invention, there is provided a flow passage into which the recording liquid is introduced, a thermal energy acting portion which is formed on the bottom surface of the flow passage and generates bubbles in the recording liquid by heat generation. An orifice that is connected to the flow path and discharges a part of the recording liquid as a recording liquid droplet by the pressure generated by the generation of the bubble, and the recording liquid that is connected to the flow path and is introduced into the flow path. In a liquid jet recording head having a liquid chamber that accommodates the liquid chamber and a supply unit that supplies the recording liquid to the liquid chamber, the flow path is formed on a single crystal silicon substrate, and a part of the single crystal silicon substrate is formed. The (111) plane is exposed by anisotropic etching, and the exposed (111) plane is directed to the downstream side in the ejection direction of the recording liquid, and the (111) faced toward the downstream side in the ejection direction of the recording liquid. The formation of the thermal energy acting portions.

According to a third aspect of the present invention, a plurality of channels for introducing the recording liquid, and a thermal energy action which is formed on the bottoms of these channels and generates bubbles in the recording liquid by heat generation. Section, an orifice that is in communication with the flow path and discharges a part of the recording liquid as a recording liquid droplet by the pressure generated by the generation of the bubbles, and is connected to the flow path and is introduced into these flow paths. In a liquid jet recording head having a liquid chamber containing the recording liquid and a supply means for supplying the recording liquid to the liquid chamber, the flow path is formed on a single crystal silicon substrate, and the single crystal silicon is formed. The (111) plane is continuously exposed by anisotropic etching over the entire width in which the plurality of channels are arranged in a part of the substrate, and the (11) plane is continuously exposed.
1) A plurality of the thermal energy acting portions were formed on the surface corresponding to the respective flow paths.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, a silicon oxide film is formed on the surface of the recess or the (111) plane by thermal oxidation, and the heat treatment is performed on the silicon oxide film. The energy acting part was formed.

According to a fifth aspect of the present invention, in the third aspect of the invention, a groove for forming a flow path is formed by photolithography on the single crystal silicon substrate on which the thermal energy acting portion is formed, and the silicon substrate is formed. A lid substrate covering the upper part of the groove was laminated on the top to form a channel.

The invention according to claim 6 is the same as in claims 1, 2 and
In the invention described in 3, 4, or 5, a single crystal silicon substrate cut out at an angle of at least 10 ° or more with respect to the (100) plane is used.

[0024]

According to the first aspect of the present invention, the concave portion is formed by anisotropic etching in a part of the single crystal silicon substrate, and the thermal energy acting portion is formed in the concave portion. Even if bubbles are generated in the recording liquid in the flow channel due to the heat generated from the thermal energy acting part, the distance to the ceiling of the channel becomes large, and the generated bubbles come into contact with the ceiling of the flow channel to prevent the flow of the recording liquid. It is prevented from shutting off, and thus the recording liquid droplets are ejected well even if the driving frequency for heating the thermal energy acting portion is increased to narrow the ejection interval of the recording liquid droplets. High-speed printing is possible.

According to the second aspect of the present invention, the (111) plane is exposed by anisotropic etching on a part of the single crystal silicon substrate, and the thermal energy acting portion is formed on the (111) plane. A good liquid jet recording head can be obtained, and the distance from the thermal energy acting portion to the ceiling of the flow passage above it becomes large, and heat is generated from the thermal energy acting portion to generate bubbles in the recording liquid in the flow passage. Also, the generated bubbles are prevented from contacting the ceiling of the flow path and interrupting the flow of the recording liquid, which increases the drive frequency for causing the heat energy acting portion to generate heat and increases the recording liquid droplets. Even if the ejection interval is narrow, the recording liquid droplets are ejected well, and high-speed printing is possible. Also,
Since the thermal energy acting portion is formed on the (111) surface facing the downstream side in the recording liquid ejection direction, the pressure of the bubbles generated by the heat generation of the thermal energy acting portion efficiently acts on the downstream side in the recording liquid ejection direction. Therefore, the recording liquid droplets are ejected from the orifice at high speed and favorably.

According to the third aspect of the present invention, the distance from the thermal energy acting portion to the ceiling of the flow passage above it is increased, and heat is generated from the thermal energy acting portion to generate bubbles in the recording liquid in the flow passage. However, it is possible to prevent the generated bubbles from contacting the ceiling of the flow path and interrupting the flow of the recording liquid, thereby increasing the driving frequency for causing the heat energy acting portion to generate heat and increasing the recording liquid droplet. Even if the ejection interval of is narrowed, the recording liquid droplets can be ejected well, and high-speed printing can be performed. In addition, by continuously exposing the (111) plane by anisotropic etching over the entire width in which a plurality of flow channels are arranged on the single crystal silicon substrate, each ( The (111) plane can be exposed more easily than when the (111) plane is exposed. Further, it is possible to easily form the thermal energy acting portion on the continuous (111) plane by photolithography or etching performed thereafter.

According to the fourth aspect of the present invention, a silicon oxide film is formed on the surface of the recess or the (111) plane by thermal oxidation, and a thermal energy acting portion is formed on the silicon oxide film. Since the formed silicon oxide film is a very dense and durable film, by using this silicon oxide film as the heat storage layer, there is no reduction in reliability due to a defect in the heat storage layer.

According to the fifth aspect of the present invention, since the groove is formed by photolithography on the single crystal silicon substrate on which the thermal energy acting portion is formed, the step created by exposing the (111) plane is filled with the photoresist. Since the flow path formed by stacking the lid substrate covering the upper part of the groove on the single crystal silicon substrate does not communicate with each other next to each other, therefore, the heat energy acting portion is caused to generate heat to generate bubbles. It is possible to prevent the pressure when generated from escaping to the adjacent flow path.

In the invention according to claim 6, a concave portion is formed by anisotropic etching by using a single crystal silicon substrate cut out at an angle of at least 10 ° or more with respect to the (100) plane. When the () surface is exposed, the inclination angle of the concave portion and the (111) plane with respect to the upper surface of the single crystal silicon substrate becomes gentle, and the formation of the thermal energy acting portion on the concave portion and the (111) surface by photolithography is enhanced. You can do it with precision.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before the description of the embodiments of the present invention, the basic structure of a liquid jet recording head to which the present invention is applied will be described with reference to FIGS. This liquid jet recording head is formed by bonding a heating element substrate 1 and a lid substrate 2, and the heating element substrate 1 is formed on a silicon substrate 3 by a wafer process by an individual electrode 4, a common electrode 5, and a heating element. (Thermal energy acting portion) 6 is formed. On the other hand, the lid substrate 2 has a groove 8 for forming a flow path 7 into which ink (recording liquid) is introduced.
And a recessed region 9 for forming a liquid chamber (not shown) for containing the ink introduced into the flow path 7 are formed by the same wafer process, and the heating element substrate 1 and the lid substrate 2 are formed. The flow path 7 and the liquid chamber are formed by joining and as shown in FIG. In the state where the heating element substrate 1 and the lid substrate 2 are bonded together, the heating element 6 is disposed on the bottom surface of the flow channel 7, and the ink in the flow channel 7 is disposed at the end of the flow channel 7. An orifice 10 is formed to eject a part of the ink droplet (ink droplet of the recording liquid).
In addition, the lid substrate 2 has an ink inlet 1 for supplying ink into the liquid chamber by a supply means (not shown).
1 is formed.

Next, the principle of ejection of ink droplets (recording liquid droplets) by the above-described liquid jet recording head is shown in FIG.
It will be explained based on. The figure (a) is a steady state, and the surface tension of the ink 12 and the external pressure are kept in equilibrium on the orifice surface. FIG. 2B shows a state in which the heating element 6 is heated and the surface temperature of the heating element 6 rapidly rises, a boiling phenomenon occurs in the adjacent ink layer, and minute bubbles 13 are scattered on the surface of the heating element 6. is there. FIG. 6C shows a state in which the adjacent ink layer that has been rapidly heated on the surface of the heating element 6 is instantly vaporized to form a boiling film, and the bubble 13 has grown. At this time, the flow path 7
The internal pressure rises as much as the bubble 13 grows, the balance with the external pressure on the orifice surface is lost, and the ink column starts to grow from the orifice 10. FIG. 7D shows a state in which the bubble 13 has grown to the maximum, and the ink 12 corresponding to the volume of the bubble 13 is pushed out from the orifice surface. At this time, the heating element 6 is already in a state in which no current flows, and the surface temperature of the heating element 6 is decreasing. The timing when the volume of the bubble 13 reaches the maximum value is slightly delayed from the application timing of the electric pulse. The same figure (e)
Indicates a state in which the bubble 13 is cooled by ink or the like and starts to shrink. It should be noted that the tip of the ink column moves forward while maintaining the pushing speed, and the bubbles 13 at the rear end of the ink column.
The ink 12 in the flow path 7 flows backward due to the pressure decrease in the flow path 7 due to the contraction of the ink, and the ink column is constricted. FIG. 6F shows a state in which the bubbles 13 are further contracted and the ink 12 comes into contact with the upper surface of the heat generating element 6, whereby the upper surface of the heat generating element 6 is further rapidly cooled. On the orifice surface, the external pressure is higher than the pressure in the flow channel 7, and therefore the meniscus is large in the flow channel 7. On the other hand, the leading end of the ink column becomes an ink drop 14, which moves toward the recording paper (not shown).
Discharge at a speed of 10 m / s. In the same figure (g), the ink 12 is supplied again into the flow path 7 by the capillary phenomenon after the ejection of the ink droplets 14 is completed, and the state returns to the same state as in the same figure (a), and the bubbles 13 are completely formed. Has disappeared.

Next, a first embodiment of the present invention will be described with reference to FIGS.
It will be described with reference to FIG. In addition, in FIG. 8 to FIG.
The same parts as those explained above are indicated by the same reference numerals, and explanations are omitted.
I will omit it. A part of the upper surface of the single crystal silicon substrate 15 is different.
The substantially V-shaped recess 16 is formed by the anisotropic etching.
The upper surface of the single crystal silicon substrate 15 is
The individual electrode 4, the common electrode 5 and the heat
A heating element 17, which is an energy acting portion, is formed. Book
Reasons for Using Single Crystal Silicon Substrate 15 in the Invention
First, silicon itself has a very high thermal conductivity (1
68W ・ m ~¹・ K ~ ¹), Because the heat dissipation characteristics are good. second
Easy to form a silicon oxide film that acts as a heat storage layer
Because you can Third, a high-purity single crystal was obtained.
And the anisotropy of the single crystal is used to make highly accurate recesses.
This is because 16 can be formed.

The step of forming the V-shaped recess 16a on the single crystal silicon substrate 15 by anisotropic etching and the single crystal silicon substrate 15 in which the recess 16a is formed will be described with reference to FIGS. .. First, FIG. 5 is a perspective view showing the single crystal silicon substrate 15 in which the concave portions 16a are formed by anisotropic etching. The crystal orientation of the single crystal silicon substrate 15 is such that the X axis and the Y axis in the figure are orthogonal to each other. The surface to be selected is selected to be the (100) surface,
Moreover, the XY axis plane (upper and lower planes) is the single crystal silicon substrate 15.
The (100) plane is selected. By doing so, the (111) plane of the single crystal silicon substrate 15 becomes
It is parallel to the Y axis and intersects the XY axis plane at an angle of about 54.7 °. The concave portions 16a formed in the single crystal silicon substrate 15 have two slopes (1
11) surface. The (111) plane has an extremely slow etching rate with an alkaline aqueous solution such as sodium hydroxide, potassium hydroxide, or humanazine as compared with other crystal planes. When the (100) plane is etched with an alkaline solution, the (111) plane is V-shaped recess 16 restricted by
a can be obtained. The width of the concave portion 16a is determined by the distance between the photoresists during photoetching and is extremely accurate. The depth of the recess 16a is
The angle between the (100) plane and the (111) plane (about 54.7
)) And the width of the upper surface, the accuracy is also extremely high. Further, the (111) plane exposed by etching is extremely smooth and highly linear.

FIG. 6 shows a recess 16 formed in a single crystal silicon substrate 15.
The step of forming a is described. First, the single crystal silicon substrate 15 having the crystal orientation as described above is prepared. In this figure, the <110> axis is perpendicular to the plane of the drawing, and the upper and lower surfaces of the single crystal silicon substrate 15 are (100) planes.
In FIG. 8A, the single crystal silicon substrate 15 is
The thermal oxide film 18 is formed on the surface by being placed in a water vapor atmosphere at about 00 to 1200 ° C. This thermal oxide film 1
It is sufficient that the thickness of 8 is about 0.3% of the etching depth. In FIG. 2B, a photoresist is applied to the entire upper surface of the thermal oxide film 18 by a known method, the photoresist is exposed by using a photographic plate, and development is performed.
It is a state where 9 is obtained. In FIG. 6C, the thermal oxide film 18 exposed between the photoresist patterns 19 is removed by an aqueous solution of hydrofluoric acid or the like to obtain an exposed portion 15a on a part of the surface of the single crystal silicon substrate 15, and then the photo resist is formed. The resist pattern 19 is removed. Next, the single crystal silicon substrate 15 in such a state is, for example, 5 to 40.
%, 80 ° C. in potassium hydroxide solution. As a result, the etching of the exposed portion 15a proceeds, but the etching progress rate of the (111) plane is (100).
Since it is about 0.3 to 0.4% of the etching progress rate of the surface, the single crystal silicon substrate 1 is
To 5 of the upper surface (which is a (100) plane as described above), an angle of tan ~ ¹ √2 (about 54.7 °) (11
The surface 1) appears, and as a result, a trapezoidal recess 16b is formed by etching as shown in FIG. When the etching is further advanced, the recess 16b becomes a V-shaped recess 16a regulated by two (111) as shown in FIG.

Considering the V-shaped recess 16a, first, so-called undercut below the end of the thermal oxide film 18 is very small, and when using high-purity sodium hydroxide, the (100) plane It is only about 0.2% of the etching depth. Therefore, the V-shaped recess 16a
The width W of ± is ± even if the error of the photomask dry plate is taken into consideration.
The accuracy can be about 5 μm. Also, the V-shaped recess 16a
The angle formed by the bottom of the is determined by the angle formed by the (111) planes (about 70.6 °). The depth “d” of the V-shaped concave portion 16a is 1 / (√2 · W), and the V-shaped concave portion 16a
The accuracy of a is extremely high. Finally, the thermal oxide film 18 used as the etching mask is removed by an aqueous solution of hydrofluoric acid or the like to obtain the single crystal silicon substrate 15 having the V-shaped recess 16a as shown in FIG. Be done.

The explanation based on FIGS. 5 and 6 is as follows.
In the description, the anisotropic etching is performed from the (100) plane of the single crystal silicon substrate 15 to form the recess 16a. However, the recess 16a (11) thus formed is actually formed.
1) Forming a heating element on the surface requires high technology.
Therefore, in the present embodiment, the single crystal silicon substrate 15 having the (100) plane as the upper surface is not used, but when the single crystal silicon substrate 15 is cut out from the ingot by a dicing saw, as shown in FIG. The single crystal silicon substrate 15 cut out from the (100) plane shown in 1 above so that the plane having a certain angle “θ” becomes the top surface is used.

Then, as shown in FIG. 4, the same step as shown in FIG. 6 is performed by using the single crystal silicon substrate 15 which is cut out from the (100) plane so that the surface having a certain angle “θ” becomes the upper surface. When the etching is performed in the process, the (111) plane is exposed and the substantially V-shaped concave portion 16 which is asymmetrical to the left and right is formed. One of the (1
11) The inclination of the surface becomes gentle. Then, by forming the heating element 17 on the (111) plane having a gentle inclination, the heating element 17 can be easily formed.

Heating element 1 on (111) plane with a gentle inclination
The reason why the formation of 7 is easy is that it is inclined (11
1) The mask pattern is not in contact with the photoresist on the surface, and this mask pattern is projected and exposed. Therefore, if the inclination of the (111) plane is too large (for example, the (111) plane of the recessed portion 16a which is symmetrical as shown in FIGS. 5 and 6), the point where the focus does not occur during exposure. As a result, good patterns cannot be formed. On the other hand, if the (111) plane has a gentle inclination, a portion out of focus cannot be formed during exposure, and good pattern formation can be performed.

Therefore, it was investigated how much the applicant could change the value of "θ" to make pattern formation impossible. The single crystal silicon substrate 15 used is
“Θ” is 0 ° (when the single crystal silicon substrate 15 is cut out along the (100) plane), 5 °, 10 °, 15 °, 2
There are 5 types at 0 °. Anisotropic etching is performed on each single crystal silicon substrate 15 to expose the (111) plane, and a pattern is formed by photolithography on the (111) plane having a gentler inclination, and a good resist pattern is obtained. I checked whether or not. The formed pattern width is 20 μm, and the photoresist used is OFPR800 manufactured by Tokyo Ohka. As a result, when “θ” is 10 ° or more, a substantially good pattern can be formed, and when 0 ° and 5 °, the pattern is blurred from the middle,
A good pattern could not be formed. That is, it was confirmed that it was impossible to form a good pattern on the (111) plane unless “θ” was set to at least 10 °.

In the single crystal silicon substrate 15 having the (111) plane exposed as described above, unnecessary photoresist is removed by a resist stripping solution after the anisotropic etching is completed, and the photoresist is used as a maskant during anisotropic etching. The thermal oxide film 18 thus formed is removed by a buffer etching solution of hydrofluoric acid and ammonium fluoride, and then cleaned to form a heat storage layer.

The heat storage layer is provided so that the heat generated by the heating element 17 does not escape to the single crystal silicon substrate 15 and is efficiently transmitted to the ink 12 which is the recording liquid. As the heat storage layer, a silicon oxide film 20 is generally used.
For example, there is a method in which the single crystal silicon substrate 15 is heated to a high temperature of 800 to 1100 ° C. in O ₂ or H ₂ O vapor to grow the silicon oxide film 20 on the single crystal silicon substrate 15. This is called thermal oxidation and is preferably used when forming a dense silicon oxide film 20 with few defects. In the present embodiment, when this thermal oxidation is performed, the inside of the furnace is subjected to a high pressure (5 kg / cm ² ) to perform the thermal oxidation (referred to as a high pressure thermal oxidation method), and a very fine defect with a thickness of 1.5 μm is formed. A small amount of silicon oxide film 20 was obtained. In addition, a liquid jet recording head is manufactured by using the single crystal silicon substrate 15 on which the silicon oxide film 20 is formed by a method described below, and the heating element 17 is driven 10 ⁹ times or more to form an ink that is a recording liquid droplet. Although the droplet 14 was discharged, there was no defect such as damage of the silicon oxide film 20.

The heat storage layer may be formed by depositing a silicon oxide film by sputtering. The silicon oxide film formed by this sputtering cannot be formed as densely as the above-mentioned thermal oxidation, but has an advantage that a thick layer can be easily formed. Here, when a liquid jet recording head is manufactured using the single crystal silicon substrate 15 on which a silicon oxide film having a thickness of 3.2 μm is formed by sputtering, a liquid jet recording head having an array density of 400 dpi (heating element is Of 28 μm × 120 μm and a resistance value of 121Ω), the energy for ejecting the ink droplet 14 required to form one pixel from the orifice 10 was 33.5 μJ. On the other hand, when a liquid jet recording head is manufactured by forming a silicon oxide film having a thickness of 1 μm by the same sputtering, the energy for ejecting the ink droplet 14 required to form one pixel from the orifice 10 is 44.7 μJ. Met. That is, it was confirmed that when the silicon oxide film serving as the heat storage layer is formed thick (3.2 μm), energy saving of about 25% can be achieved as compared with the case where it is formed thin (1 μm).

Next, the formation of the heating element 17, the individual electrode 4 and the common electrode 5 on the single crystal silicon substrate 15 on which the silicon oxide film 20 is formed will be described with reference to FIG.
First, on the silicon oxide film 20 are formed heat generating layer 17a, as the useful material constituting the heat generating layer 17a, a mixture of tantalum -SiO _2, tantalum nitride, nichrome, silver - palladium Alloy, silicon semiconductor, or hafnium, lanthanum, zirconium, titanium, tantalum, tungsten, molybdenum, niobium,
Examples thereof include borides of metals such as chromium and vanadium. Among the metal borides, hafnium boride has the best characteristics, followed by zirconium boride, lanthanum boride, tantalum boride, vanadium boride, and niobium boride in this order.

The heating element layer 17a can be formed using the above-mentioned materials by a method such as electron beam evaporation or sputtering. A portion of the heating element layer 17a sandwiched between the individual electrode 4 and the common electrode 5 serves as a heating element 17. The film thickness of the heating element 17 is determined according to its area, material and shape, and the actual power consumption etc. so that the amount of heat generation per unit time is as desired, but in the normal case , 0.001 to 5 μm, preferably 0.01 to 1 μm. In this embodiment, Ta · S
2000 Å of SiO ₂ is sputtered.

As the material for the individual electrodes 4 and the common electrode 5, many of the commonly used electrode materials are effectively used. Specifically, for example, Al, Ag, A
Examples include u, Pt, and Cu. These are used and provided at a predetermined position by a technique such as vapor deposition, and have a predetermined size, shape, and thickness. In this example, Al was formed to a thickness of 1.4 μm by sputtering.

A protective layer 2 is formed on the heating element 17 and the electrodes 4 and 5.
1 is formed, the characteristics required for the protective layer 21 do not prevent the heat generated in the heating element 17 from being effectively transferred to the ink 12, and
It means to protect 7. Examples of useful materials for forming the protective layer 21 include silicon oxide, silicon nitride, magnesium oxide, aluminum oxide, tantalum oxide, zirconium oxide, and the like. These are formed by a method such as electron beam evaporation or sputtering. It is formed. Ceramic materials such as silicon carbide and aluminum oxide (alumina) are also suitable materials. The thickness of the protective layer 21 is usually 0.01 to 10 μm.
m, preferably 0.1-5 μm, optimally 0.1-3 μm
Is. In this embodiment, silicon oxide (SiO ₂ ) is formed to a thickness of 1.2 μm by sputtering. Further, in this embodiment, in order to protect the region of the heating element 17 from cavitation destruction due to generation of bubbles, Ta was formed as the cavitation-resistant protective layer 22 on the protective layer 21 by sputtering to a thickness of 4000 Å.

As described above, the single crystal silicon substrate 1
The concave portion 16 is formed on the insulating layer 5 by anisotropic etching, and the heating element 17, the electrodes 4, 5 and the protective layers 21, 22 and the like are further formed to form the heating element substrate 23. Next, the liquid jet recording head is formed by joining the lid substrate to the heating element substrate 23. The lid substrate 2 (shown in FIGS. 8 to 10) is formed on the heating element substrate 23. The lid substrate 2 is formed with a groove 8 for forming a flow path through which the ink 12 is introduced, and a recessed region 9 for forming a liquid chamber for containing the ink 12 introduced through the flow path. .) Are joined to form a flow path or a liquid chamber, the adjacent flow paths are connected to each other by the concave portion 16, and the pressure for ejecting the ink droplet 14 escapes to the adjacent flow path. The ink droplets 14 cannot be ejected well.

Therefore, in this embodiment, as shown in FIG. 3, the heating element substrate 23 in which the groove 24 and the recessed region 25 are formed by the photolithography technique using a photoresist and the groove 24 and the recessed region 25 are formed. A flow path 27 into which the ink 12 is introduced by joining the lid substrate 26 on the top.
And a liquid chamber 28 containing the ink 12 introduced into the flow path 27
A liquid jet recording head having the following is formed, and a forming process of this liquid jet recording head will be described based on FIG. In the description of FIG. 3, the concave portion 16 is omitted from the heating element substrate 23 in order to prevent the drawing from becoming complicated, but in reality, the concave portion 16 is formed as shown in FIGS. 1 and 2. The formed heating element substrate 23 is used. FIG. 6A shows a state in which the heating element substrate 23 is covered with the dry film photoresist 29. FIG. 2B shows a state in which a photomask 30 for forming the groove 24 and the recessed region 25 is aligned with the heating element 17 and covers the dry film photoresist 29. In the same figure (c), the groove 24 and the concave region 2 are formed by exposing and developing.
5 is formed. A taper portion 31 is formed on the tip side of the groove 24. In the same drawing (d), the lid substrate 26 is bonded onto the heating element substrate 23, and the flow path 27 and the liquid chamber 2 are joined.
8 is formed. The (111) surface on which the heating element 17 is formed faces the downstream side (orifice 10 side) in the ejection direction of the ink 12 flowing in the flow path 27.
FIG. 6E is a cross-sectional view taken along the line BB of FIG. 7D, in which the orifice 10 is formed by cutting the line CC of FIG. A recording head is formed.

Here, the dry film photoresist 2 is used.
9 is, for example, Audil SY-3 manufactured by Tokyo Ohka.
No. 25 has strong ink corrosion resistance and is preferably used. The dry film photoresist 29 is laminated on the heating element substrate 23 by applying heat and pressure. Therefore, even if the heating element substrate 23 has the recess 16 as in the present embodiment, the dry film photoresist 29 softened by heat and pressure is used.
Fills the recess 16 and finally forms each flow path 2
7 does not communicate with each other next to each other, and therefore the pressure does not escape to the adjacent flow passage 27, and the flow passage 27 is excellent.

The above is the dry film photoresist 2
Although the example using 9 is described, a liquid photoresist can be used instead of the dry film photoresist 29. As such a liquid photoresist, for example, BMRS1000 manufactured by Tokyo Ohka can be preferably used. As a method for applying the liquid photoresist to the heating element substrate 23, a spin coating method, a dipping method, or the like can be preferably used. However, in any method, the liquid photoresist can easily fill the recess 16 of the heating element substrate 23. Therefore, each flow path 27 that is finally formed is
Adjacent ones do not communicate with each other, and therefore, pressure does not escape to the adjacent flow passage 27, and a good flow passage 27 is formed.

The liquid jet recording head according to the present invention formed in the above steps is the liquid jet recording head shown in FIGS. 8 to 10 (the liquid jet recording head of the conventional example).
The discharge efficiency is much higher than that of. Also, high speed driving is possible. Hereinafter, the comparison results of the ejection efficiency and the like between the liquid jet recording head of the conventional example shown in FIGS. 8 to 10 and the liquid jet recording head according to the present invention will be described. In the liquid jet recording head according to the present invention used for this comparison, “θ” was set to 15 ° and a 1.5 μm thick silicon oxide film was formed by the high pressure thermal oxidation method as the heat storage layer. On the other hand, in the conventional liquid jet recording head, a silicon oxide film having a thickness of 1.5 μm is formed as a heat storage layer by sputtering.

[0052]

[Table 1]

As is clear from the above description, when the ink droplets 14 are ejected under substantially the same heating element size and driving conditions, the liquid jet recording head according to the present invention having the recess 16 is formed. Since the pressure of the generated bubbles can be exerted toward the orifice 10 side, the pressure can be effectively used for ejecting the ink droplets 14, and stable ejection having a very high flight speed can be performed. Further, since the heating element 17 is formed at a position lower than the other bottom surface portion of the flow path 27, the generated bubbles come into contact with the ceiling portion of the flow path 27 and shut off the flow of the ink 12 in the flow path 27. Therefore, the maximum driving frequency can be increased and high-speed recording can be performed. In addition, the heating element 17
Has a life of 1.5μ by sputtering as a heat storage layer.
When the silicon oxide film having a thickness of m was formed, the number of driving times of the heating element was 10 ^8. However, when the silicon oxide film 20 having a thickness of 1.5 μm was formed by the high pressure thermal oxidation method as the heat storage layer. The number of times that the heating element 17 was driven was 10 ⁹ or more.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those described with reference to FIGS. 1 to 6 are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, when the concave portion 32 having the (111) plane exposed is formed on the single crystal silicon substrate 15 by anisotropic etching, the photoresist pattern shown in FIG. The recessed portion 32 is formed. Then, the heating element 1 is placed in each of the recesses 32.
7 are formed one by one, and further, each recess 32 and the heating element 1 are formed.
The flow path 27 is formed so as to correspond to No. 7.

By independently forming the recesses 32 on the single crystal silicon substrate 15 in this manner, the grooves 24 are formed in the photoresist (dry film photoresist, liquid photoresist) when forming the flow path. Since the region to be formed does not cover the (111) plane, photolithography for forming the groove 24 can be performed with extremely high accuracy. Furthermore, even if the lid substrate 2 having the groove 8 for a flow channel as shown in FIGS. 8 to 10 is used, the adjacent flow channels do not communicate with each other, and pressure is applied to the adjacent flow channels. Since there is no escape, a good flow path can be formed. Further, such a lid substrate 2 can be made with high precision by etching a photosensitive glass or molding a resin such as polysulfone. And each of the independent recesses 32
The heating element substrate having the heating element 17 formed therein and the lid substrate 2 are
Although it may be bonded by a bonding agent such as an adhesive agent, even if both are pressed by a spring member (for example, a leaf spring), they can be mechanically pressed very easily and accurately, and function as a liquid jet recording head. Can be fully fulfilled. In addition,
At this time, a sealant may be auxiliary disposed between the both while mechanically pressing them to prevent the ink 12 from leaking.

[0056]

According to the first aspect of the present invention, there is provided a flow passage into which the recording liquid is introduced, and a thermal energy acting portion which is formed on the bottom surface of the flow passage and generates bubbles in the recording liquid by heat generation. An orifice which is connected to the flow path and discharges a part of the recording liquid as a recording liquid droplet by pressure generated by the generation of the bubbles; and an orifice which is connected to the flow path and is introduced into the flow path. In a liquid jet recording head having a liquid chamber containing a recording liquid and a supply means for supplying the recording liquid to the liquid chamber, the flow path is formed on a single crystal silicon substrate, and one of the single crystal silicon substrates is formed. To form a recess in the area by anisotropic etching,
Since the thermal energy acting portion is formed in this concave portion, the distance from the thermal energy acting portion to the ceiling of the flow passage above it becomes large, and heat is generated from the thermal energy acting portion to cause bubbles in the recording liquid in the flow passage. Even if it is generated, it is possible to prevent the bubbles from contacting the ceiling of the flow path and interrupting the flow of the recording liquid, and thereby increasing the drive frequency for heating the thermal energy acting portion to perform recording. Even if the discharge interval of the liquid droplets is narrowed, the recording liquid droplets can be discharged well, and high-speed printing can be performed.

According to a second aspect of the present invention, there is provided a flow path into which the recording liquid is introduced, a thermal energy acting section which is formed on the bottom surface of the flow path and which generates bubbles in the recording liquid by heat generation. An orifice that is connected to the flow path and discharges a part of the recording liquid as a recording liquid droplet by the pressure generated by the generation of the bubble, and the recording liquid that is connected to the flow path and is introduced into the flow path. In a liquid jet recording head having a liquid chamber that accommodates the liquid chamber and a supply unit that supplies the recording liquid to the liquid chamber, the flow path is formed on a single crystal silicon substrate, and a part of the single crystal silicon substrate is formed. The (111) plane is exposed by anisotropic etching, the exposed (111) plane is directed to the downstream side in the ejection direction of the recording liquid, and the (111) plane is directed to the downstream side in the ejection direction of the recording liquid. Since the thermal energy acting portion is formed in the above, a very accurate liquid jet recording head can be obtained, and the distance from the thermal energy acting portion to the ceiling of the flow path above it becomes large, so that the thermal energy acting portion is increased. Even if bubbles are generated in the recording liquid in the channel due to heat generated from the section, it is possible to prevent the bubbles from contacting the ceiling of the channel and blocking the flow of the recording liquid. Even if the ejection frequency of the recording liquid droplets is narrowed by increasing the driving frequency for heating the energy acting portion, the recording liquid droplets can be ejected well and high-speed printing can be performed. Further, since the thermal energy acting portion is formed on the (111) surface facing the downstream side in the recording liquid ejection direction, the pressure of the bubble generated by the heat generation of the thermal energy acting portion efficiently ejects the recording liquid. The recording liquid droplets can be discharged from the orifice at high speed, and the discharge speed can be increased to improve the accuracy of landing on the recording medium and improve the image quality. It has the effect of being able to

According to a third aspect of the present invention, a plurality of channels for introducing the recording liquid, and a thermal energy action for forming bubbles in the recording liquid by heat generation are formed on the bottoms of these channels. Section, an orifice that is in communication with the flow path and discharges a part of the recording liquid as a recording liquid droplet by the pressure generated by the generation of the bubbles, and is connected to the flow path and is introduced into these flow paths. In a liquid jet recording head having a liquid chamber containing the recording liquid and a supply means for supplying the recording liquid to the liquid chamber, the flow path is formed on a single crystal silicon substrate, and the single crystal silicon is formed. The (111) plane is continuously exposed by anisotropic etching over the entire width in which the plurality of channels are arranged in a part of the substrate, and the (11) plane is continuously exposed.
1) Since a plurality of the thermal energy acting portions are formed on the surface so as to correspond to the respective flow passages, the distance from the thermal energy acting portion to the ceiling of the flow passage above it becomes large, and Even if bubbles are generated in the recording liquid in the channel due to heat generation, it is possible to prevent the bubbles from contacting the ceiling of the channel and interrupting the flow of the recording liquid.
As a result, even if the driving frequency for heating the thermal energy acting portion is increased and the ejection interval of the recording liquid droplets is narrowed, the recording liquid droplets can be ejected favorably and high-speed printing is performed. Furthermore, since the (111) plane is continuously exposed by anisotropic etching over the entire width in which the plurality of flow paths in the single crystal silicon substrate are arranged, it is possible to correspond to each flow path. Individually (111)
The (111) plane can be exposed more easily than the case where the (111) plane is exposed, and the continuous (111) plane is exposed.
There is an effect that the thermal energy acting portion can be easily formed on the surface by photolithography or etching.

According to the fourth aspect of the present invention, since the silicon oxide film is formed on the surface of the recess or the (111) plane by thermal oxidation and the thermal energy acting portion is formed on this silicon oxide film, it is formed by thermal oxidation. Since the formed silicon oxide film is a very dense and durable film, by using this silicon oxide film as the heat storage layer, it is possible to prevent deterioration of reliability due to a defect of the heat storage layer and improve durability. And so on.

According to a fifth aspect of the invention, in the third aspect of the invention, a groove is formed by photolithography on the single crystal silicon substrate on which the thermal energy acting portion is formed, and the upper portion of the groove is formed on the silicon substrate. Since the lid substrate for covering is laminated to form the flow path, the step created by exposing the (111) plane when forming the groove can be filled with the photoresist, and thus the lid for covering the upper portion of the groove is formed. The channels formed by stacking the substrate on the single crystal silicon substrate do not communicate with each other next to each other.Therefore, the pressure when heat is generated in the thermal energy acting part to generate bubbles causes the flow of the adjacent flow to flow. It is possible to prevent the ink from escaping to the path and to efficiently eject the ink droplets.

The invention according to claim 6 is the same as claim 1, 2 or
In the invention described in 3, 4, or 5, since the single crystal silicon substrate cut out at an angle of at least 10 ° or more with respect to the (100) plane is used, the concave portion is formed in the single crystal silicon substrate by anisotropic etching. Formed (11
When the 1) plane is exposed, the inclination angle of the concave portion or the (111) plane with respect to the upper surface of the single crystal silicon substrate becomes gentle, so that the thermal energy acting portion is formed on the concave portion or the (111) plane by photolithography. It has an effect that it can be performed with high accuracy.

[Brief description of drawings]

FIG. 1 is a perspective view showing a heating element substrate in a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a manufacturing process diagram of a liquid jet recording head.

FIG. 4 is a side view showing a state in which a single crystal silicon substrate to be used is cut out from an ingot and a recess formed in this single crystal silicon substrate by anisotropic etching.

FIG. 5 is a perspective view showing a state in which a concave portion is formed by performing anisotropic etching from the (100) plane of a single crystal silicon substrate.

FIG. 6 is a process drawing showing a process of anisotropically etching a (100) plane of a single crystal silicon substrate to form a recess.

FIG. 7 is a perspective view showing a single crystal silicon substrate in which a recess is formed in the second embodiment of the present invention.

FIG. 8 is a perspective view showing a liquid jet recording head of a conventional example.

FIG. 9 is a perspective view showing a state in which a liquid jet recording head of a conventional example is separated into a heating element substrate and a lid substrate.

FIG. 10 is a perspective view showing a state where the lid substrate is viewed from the back surface side.

FIG. 11 is an explanatory diagram showing the principle of ink droplet ejection in the liquid jet recording head.

[Explanation of symbols]

 10 Orifice 12 Recording Liquid 13 Bubble 14 Recording Liquid Small Droplet 15 Single Crystal Silicon Substrate 16, 32 Recess 17 Thermal Energy Acting Part 20 Silicon Oxide Film 24 Groove 26 Lid Substrate 27 Channel 28 Liquid Chamber

Claims (6)

[Claims] 1. A flow passage into which a recording liquid is introduced, a thermal energy acting portion which is formed on a bottom surface of the flow passage and generates bubbles in the recording liquid by heat generation, and is connected to the flow passage. An orifice that discharges a part of the recording liquid as recording liquid droplets by the pressure accompanying the generation of the bubbles, and a liquid chamber that is connected to the flow channel and that stores the recording liquid that is introduced into the flow channel. A liquid jet recording head having a supply means for supplying the recording liquid to the liquid chamber, wherein the flow path is formed on a single crystal silicon substrate and a recess is formed in a part of the single crystal silicon substrate by anisotropic etching. And a thermal energy acting portion is formed in the concave portion. 2. A flow passage into which the recording liquid is introduced, a thermal energy acting portion which is formed on a bottom surface of the flow passage and generates bubbles in the recording liquid by heat generation, and is connected to the flow passage. An orifice that discharges a part of the recording liquid as recording liquid droplets by the pressure accompanying the generation of the bubbles, and a liquid chamber that is connected to the flow channel and that stores the recording liquid that is introduced into the flow channel. In a liquid jet recording head having a supply unit that supplies the recording liquid to the liquid chamber, the flow path is formed on a single crystal silicon substrate, and a portion of the single crystal silicon substrate is anisotropically etched ( The (111) surface is exposed and exposed (1
The liquid jet recording head is characterized in that the heat energy acting portion is formed on the (111) surface facing the downstream side in the discharge direction of the recording liquid and the (111) surface facing the downstream side in the discharge direction of the recording liquid. 3. A plurality of channels for introducing a recording liquid,
A thermal energy acting portion that is formed on the bottom surface of these flow paths and that generates bubbles in the recording liquid by heat generation, and a portion of the recording liquid that is connected to the flow paths and that is accompanied by the pressure generated by the bubbles. An orifice for discharging a recording liquid droplet as a recording liquid, a liquid chamber for communicating with the flow passage and containing the recording liquid introduced into these flow passages, and a supply means for supplying the recording liquid to the liquid chamber In the liquid jet recording head having the above, the flow path is formed on a single crystal silicon substrate, and anisotropic etching is performed over the entire width in which the plurality of flow paths are arranged in a part of the single crystal silicon substrate. The (111) plane is continuously exposed by, and a plurality of the thermal energy acting portions are formed on the continuously exposed (111) plane so as to correspond to the respective flow paths. Cum recording head. 4. The silicon oxide film is formed on the surface of the recess or the (111) plane by thermal oxidation, and the thermal energy acting part is formed on the silicon oxide film. The liquid jet recording head described. 5. A groove for forming a flow path is formed by photolithography on a single crystal silicon substrate having a thermal energy acting portion, and a lid substrate covering the upper portion of the groove is laminated on the silicon substrate. The liquid jet recording head according to claim 3, wherein a flow path is formed. 6. The liquid jet according to claim 1, wherein a single crystal silicon substrate cut out at an angle of at least 10 ° or more with respect to the (100) plane is used. Recording head.